1. Field of the Invention
The present invention relates to an engine system having an engine, in which a catalyst is placed in an exhaust gas passage.
2. Description of Related Art
Conventionally, there is known an engine technology in which a catalyst is placed in an exhaust gas passage in order to remove condensed water generated by condensation of moisture in exhaust gas. JP 2010-216399 A discloses a configuration of inhibiting generation of the condensed water in an exhaust gas passage by controlling ignition timing and an air-fuel ratio on the basis of a temperature of the exhaust gas.
If the engine is started in a cold state, the exhaust gas condenses when the exhaust gas passes the exhaust gas passage, and the condensed water is generated. If operation of the engine is continued, since the temperature of the exhaust gas passage is also increased, the condensed water once condensed is also evaporated and removed. However, if the operation of the engine is stopped for a short time, the condensed water remains in the exhaust gas passage. If such a short time operation is repeated, the amount of the remaining condensed water cannot be ignored, and there is a possibility that the catalyst in the exhaust gas passage is immersed.
JP 2010-216399 A discloses a configuration of inhibiting the condensed water generated during the operation of the engine. However, JP 2010-216399 A does not disclose a configuration of discharging the condensed water remaining in the exhaust gas passage. Although the condensed water can be discharged by providing a drainage passage in the exhaust gas passage, it is sometimes difficult to install the drainage passage in terms of layout or maintenance of the engine.
It is an object of the present invention to provide a configuration that can discharge the condensed water remaining in an exhaust gas passage of an engine in which a catalyst is placed in an exhaust gas passage.